Once upon a time I was a cellular phone network technician with one of the big companies. We could do lots of things like APPROXIMATE your location based on signal strength, figure out what direction you are travelling in based on changes in signal strength, and listen in while you are making a call (for maintenance purposes only of course). In addition, I would very rarely be required to cooperate with some law enforcement agency (local agencies only, never worked with feds for a wiretap or to identify the location a call originated from, did this 2x in 4 years in a metropolitan area of 4 million people). It is also worth mentioning that standard cellular radio frequency maintenance equipment can be used to listen to calls within a given proximity, illegal for civillians, ok for phone comany technicians, requires warrant/official paperwork for LE). When not in active use but turned on your cell phone transmits a period keep alive signal (mobile identification number MIN and electronic serial number ESN) to the network which is routed through a national system that says your phone is available to receive calls and what cell tower you are closest to. It does not transmit voice when not actively involved in a call. To do so would overtax the wireless network. If the FBI has the capability to remotely activate your phone and eavesdrop I have never seen it and there is NO WAY they could do it without the help of the phone company technicians (as in need official paperwork), I repeat NO WAY, the network is much to fucking complicated for them to pull that off alone. While whispering fuck you Bush into your phone might be palliative for the disaster that has been the last 8 years it is unlikely he will receive your message.